Transcript for Parts of the East Coast and Heartland on Alert for More Severe Weather

Severe weather targeting parts of the country this evening nearly thirteen million Americans in the path of the storms tonight. We've already seen the flooding in Maryland drivers trying to navigate the washed out roads. And they were people trapped under an overpass today who had to be rescued you could see right there the water a simply -- -- in their cars to handle. I want to bring in chief meteorologist Cecily Tynan for mark Philly station WPI tracking this on the -- -- it's a -- you were telling me there was a lot more rain to come. -- certainly is more flooding on the way this -- the trouble spot today and narrow band of storms between DC and Baltimore. But it sat there the rain falling at the rate of more than three inches an hour that's what caused the flash flooding but the next 48 hours. It's going to be widespread we're looking at the potential for more than four inches of rain all the way from the Gulf Coast up into the mid Atlantic on already saturated ground. With the risk of more flash flooding -- loyal viewers in -- you're gonna feel this in the meantime there's also severe weather -- -- -- it comes tomorrow exactly two areas of severe weather one of them. Across the plains from Texas it's -- Nebraska another one in the mid Atlantic from -- to Pittsburgh. The main threat will be damaging straight line winds but also the potential. For large hail and David we're in an atmosphere traffic jams this unsettled weather will be lasting right through the end of the week or year old Cecily Tynan with the senator thanks to -- and -- VI.

This transcript has been automatically generated and may not be 100% accurate.

As many as 200 people are still unaccounted for while some flood victims are allowed to go home.

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